1. Field of the Invention
The present invention relates to a silicone impression material used when producing a dental prosthesis in dentistry. More particularly, the present invention relates to a dental silicone impression material composition having high viscosity of a kneaded material before curing and low hardness after curing.
2. Description of the Conventional Art
In a dental treatment, a silicone impression material including a silicone resin as a main component, an alginate impression material containing alginate as a main agent, calcium sulfate as a curing material, which is cured under the existence of water, and a polyether-based impression material including a polyether resin as a main component have been used.
According to the aging of population, a necessity of dental treatments at home has increased. In the home dental treatments, the alginate impression material has been widely used, because the alginate impression material has low cost, can be easily removed from an oral cavity because of having low hardness, and can be applied to a complicated row of teeth of a patient. Further, since there are many old people whose vomiting reflex is weak, the alginate impression material having high viscosity of a kneaded material and hardly flowing into the depth of a throat has been preferably used. The alginate impression material shrinks by drying and impression accuracy decreases. For preventing this tendency, it is necessary to rapidly pour gypsum into the material after taking impression. However, since bringing materials or tools for pouring the gypsum is complicated, the alginate impression material has not been proper for a home treatment. Accordingly, developing a silicone impression material having similar characteristics to the alginate impression material has been desired, that is, high viscosity of a kneaded material before curing so as to hardly flow into the depth of a throat, and low hardness after curing which is a similar level to the alginate impression material.
Furthermore, when a dental technician produces a dental prosthesis with high accuracy, a silicone impression material having higher accuracy than the alginate impression material has been used. However, since the conventional silicone impression material has high hardness after curing, an operation for sealing an undercut of a surplus part with wax or the like and thereby easily removing the silicone impression material after curing from an oral cavity is necessary. More specifically, currently, since the number of a patient suffering from periodontitis even though having many remaining teeth has been increasing, an operation for treating the undercut more accurately and minutely has been necessary. Therefore, a silicone impression material which does not need the undercut treatment, namely, a silicone impression material having low hardness after curing and being easily removed from an oral cavity has been desired.
As a method for solving the aforementioned problems of the conventional silicone impression material, a composition for a dental impression which can prevent dropping of a kneaded material has been discussed (refer to Japanese Patent Application Laid-Open No. 2009-203196), and the composition is produced by adding hydrocarbon-based oily components to a composition including an organosiloxane having a specific structure, a polyether, an organohydrogenpolysiloxane, an inorganic filler, a nonionic surfactant, and a silicone-soluble platinum compound. Further, a silicone composition for a dental impression has been discussed (refer to Japanese Patent Application Laid-Open No. H10-72307), and the silicone composition includes an organopolysiloxane having a specific structure, an organohydrogenpolysiloxane, a silicone-soluble platinum compound, a fine powdery silica having a specific surface area and being subjected to hydrophobic treatment and a methylphenyl polysiloxane. However, although these impression materials do not cause dropping of a kneaded material, these impression materials have low viscosity of the kneaded material before curing because of including the hydrocarbon-based oily components with low viscosity. Thus, since an oral mucosa cannot be fully pressurized, the accuracy of the impression is insufficient.